Add EmulatorRunner for emulator CLI operations

src/Xamarin.Android.Tools.AndroidSdk/Runners/EmulatorRunner.cs

@@ -0,0 +1,110 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Xamarin.Android.Tools
+{
+	/// <summary>
+	/// Runs Android Emulator commands.
+	/// </summary>
+	public class EmulatorRunner
+	{
+		readonly Func<string?> getSdkPath;
+		readonly Func<string?>? getJdkPath;
+
+		public EmulatorRunner (Func<string?> getSdkPath)
+			: this (getSdkPath, null)
+		{
+		}
+
+		public EmulatorRunner (Func<string?> getSdkPath, Func<string?>? getJdkPath)
+		{
+			this.getSdkPath = getSdkPath ?? throw new ArgumentNullException (nameof (getSdkPath));
+			this.getJdkPath = getJdkPath;
+		}
+
+		public string? EmulatorPath {
+			get {
+				var sdkPath = getSdkPath ();
+				if (string.IsNullOrEmpty (sdkPath))
+					return null;
+
+				var ext = OS.IsWindows ? ".exe" : "";
+				var path = Path.Combine (sdkPath, "emulator", "emulator" + ext);
+
+				return File.Exists (path) ? path : null;
+			}
+		}
+
+		public bool IsAvailable => EmulatorPath is not null;
+
+		void ConfigureEnvironment (ProcessStartInfo psi)
+		{
+			var sdkPath = getSdkPath ();
+			if (!string.IsNullOrEmpty (sdkPath))
+				psi.EnvironmentVariables ["ANDROID_HOME"] = sdkPath;
+
+			var jdkPath = getJdkPath?.Invoke ();
+			if (!string.IsNullOrEmpty (jdkPath))
+				psi.EnvironmentVariables ["JAVA_HOME"] = jdkPath;
+		}
+
+		public Process StartAvd (string avdName, bool coldBoot = false, string? additionalArgs = null)
+		{
+			if (!IsAvailable)
+				throw new InvalidOperationException ("Android Emulator not found.");
+
+			var args = $"-avd \"{avdName}\"";
+			if (coldBoot)
+				args += " -no-snapshot-load";
+			if (!string.IsNullOrEmpty (additionalArgs))
+				args += " " + additionalArgs;
+
+			var psi = new ProcessStartInfo {
+				FileName = EmulatorPath!,
+				Arguments = args,
+				UseShellExecute = false,
+				CreateNoWindow = true
+			};
+			ConfigureEnvironment (psi);
+
+			var process = new Process { StartInfo = psi };
+			process.Start ();
+
+			return process;
+		}
+
+		public async Task<List<string>> ListAvdNamesAsync (CancellationToken cancellationToken = default)
+		{
+			if (!IsAvailable)
+				throw new InvalidOperationException ("Android Emulator not found.");
+
+			var stdout = new StringWriter ();
+			var psi = new ProcessStartInfo {
+				FileName = EmulatorPath!,
+				Arguments = "-list-avds",
+				UseShellExecute = false,
+				CreateNoWindow = true
+			};
+			ConfigureEnvironment (psi);
+
+			await ProcessUtils.StartProcess (psi, stdout, null, cancellationToken).ConfigureAwait (false);
+
+			var avds = new List<string> ();
+			foreach (var line in stdout.ToString ().Split ('\n')) {
+				var trimmed = line.Trim ();
+				if (!string.IsNullOrEmpty (trimmed))
+					avds.Add (trimmed);
+			}
+
+			return avds;
+		}
+	}
+}
+